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PEDOT:PSS-Coated Screen-Printed Graphene–Carbon Ink-Based Humidity and Temperature Sensor | IEEE Journals & Magazine | IEEE Xplore

PEDOT:PSS-Coated Screen-Printed Graphene–Carbon Ink-Based Humidity and Temperature Sensor


Abstract:

This work presents a multifunctional humidity and temperature sensor, fabricated on a flexible polyvinyl chloride (PVC) substrate using facile screen printing and drop ca...Show More

Abstract:

This work presents a multifunctional humidity and temperature sensor, fabricated on a flexible polyvinyl chloride (PVC) substrate using facile screen printing and drop casting. The sensor comprises screen-printed graphene–carbon (G–C) layer coated with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The sensor displays good sensing performance (~1%/%RH) toward wide humidity range (25%RH–90%RH) at room temperature (RT; 27°C ± 2°C). The influence of operating temperature on humidity sensing performance is examined in the temperature range of 15 °C–55 °C and a nearly linear relation (with Adj. R^{2} of value 0.959) is observed toward change in temperature (35 °C–55 °C). Furthermore, the temperature sensing performance of the sensor is analyzed in a 15 °C–35 °C temperature range. The sensor displays good performance with a temperature coefficient of resistance (TCR) as −3.18%°C and −1.3%°C for 15 °C–25 °C and 25 °C–35 °C, respectively. Other important sensing characteristics, such as repeatability, hysteresis, response, and recovery times, are also analyzed and presented here.
Published in: IEEE Journal on Flexible Electronics ( Volume: 2, Issue: 2, March 2023)
Page(s): 111 - 118
Date of Publication: 12 December 2022
Electronic ISSN: 2768-167X

Funding Agency:


I. Introduction

Humidity and temperature sensing is of significant interest in applications, such as environment monitoring [1], personal healthcare [2], [3], [4], [5], electronic skin (e-Skin) [6], [7], [8], food packaging [9], [10], [11], and agriculture [12], [13]. The regular and continuous monitoring of these parameters is important in the above applications. For example, most of greenhouse plants/crops require relative humidity in/around the range of 40%–80% [14], [15], [16] and optimal air temperatures in/around the range of 17 °C–27 °C [13], [15], [17]. This means that it is important to maintain the desired levels of humidity and temperature to ensure high growth rates of greenhouse crops/plants. This need for humidity and temperature measurements calls for cost-effective sensors, and as a result, a wide variety (e.g., capacitive, resistive) of temperature and humidity sensors have been explored [6], [7], [18], [19], [20], [21], [23]. However, complex synthesis, nonflexible form factors, and cost-ineffective fabrication hinder their widespread use. In this regard, printed sensors on flexible substrates offer an attractive route for flexible electronics applications [24], [25], [26]. The capability to choose the printing ink, substrate, and the flexibility of designing the electrode with desired pattern offers numerous opportunities to enhance the performance of these sensors. Furthermore, resource-efficient printing could improve the commercial viability of these sensors [27].

References

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